378 THE ARACHNOIDAE. S$ 307. 
nal side of, or underneath the basilar article. It is erected when the 
animal, for defence, or for the seizure of its prey, inflicts a poisonous. 
wound; and, for this purpose, the excretory duct of a poison-gland 
opens at the apex of each of these hooks.” The first pair of maxillae is 
changed, with the Araneae, into very long tactile, and with the Phrynidae,. 
into prehensile organs. Their basilar articles form two upwardly directed 
prominences, which are contiguous at their bristly, internal borders, and 
thereby cover the entrance of the oral cavity. As the Araneae bruise,. 
by means of these prominences, their prey which they have seized and 
taken into their mouth, these parts may be regarded as rudimentary 
maxillae. 
The entrance of the Oral cavity is surrounded, with most Arachnoidae, 
by a soft, unequal border. This may be regarded, in part, as an upper and 
under lip, and partly as a tongue.“ The orifice and cavity of the mouth 
are often provided with small hairs pointing inwards, among which are 
sometimes observed horny ridges, which serve, probably, as teeth. The 
Araneae have this peculiarity, that their large oral cavity has a groove on 
the median line of the palate, which is continuous into the esophagus. 
Its lateral borders may be so approximated that it is changed into a canal. 
This apparatus is certainly very serviceable to these animals in sucking 
their prey, after it has been punctured repeatedly, and taken into the 
mouth. ; 
With very many Arachnoidae, the food, before reaching the proper 
digestive tube, traverses a very short cesophagus, 7 
With the Araneae, this canal is geniculate, of a horny consistence, and, 
at the point where it enters the stomach, it presents a prismatic muscular 
enlargement on which is inserted a large muscle arising from the centre 
of the dorsal shield and passing through the central opening of the 
stomach." This serves probably as a sucking apparatus during the pre- 
hension and deglutition of food. With the Tardigrada, the oesophagus 
terminates also by a muscular apparatus of this kind, which, with Macro- 
biotus, and Emydium, is spheroidal, and with Minesium, cylindrical.% 
§ 307. 
The Intestinal canal of the Arachnoidae is formed after two different. 
types. 
1. With the Tardigrada, Acarina, Pycnogonidae, Opilionina, Solpugi- 
dae, and Araneae, the stomach has a greater or less number of caecal 
9 See § 315. De of the Py idae; but, ut tly, 
10 See Treviranus, Bau d. Arach. Taf. IT. fig. 
14-16, r., and Brandt, Mediz. Zool. II. Taf. XV. 
fig. 9, 18, b. 
ll With the Araneae, and Scorpionidae, the 
entrance of the mouth has a tumid, pilose upper 
lip. With the Opilionina, there are several such 
tumefactions, but with the Pycnogonidae, the oral 
orifice is prolonged, snout-like, between the max~ 
illae. 
12 See Lyonet, loc. cit. p. 401, Pl. XXI. fig. 4, 
5, and Duges, Ann. d. Sc. Nat. VI. p. 178. 
18 With the Acarina, Pycnogonidae, and Araneae. 
Quatrefages (Compt. rend. XIX. 1844, p. 1152) 
thinks he has observed a ciliated epithelium in the 
he found that he was deceived, and that vibratile 
organs were wanting here as with all the Arthro- 
poda, 
14 Brandt, Mediz. Zool. I. p. 89, Taf. XV. fig. 
6, b., or Ann. d. Sc. Nat. XIII. p. 183, Pl. IV. fig. 
2. b. 
15 This suctorial apparatus appears to have been 
well described and understood by Wasmann (loc. 
cit. p. 10, fig. 13, i. m.); but, already before this, 
Lyonet (loc. cit. p. 402, Pl. XXL. fig. 4,C D E, 
had rightly perceived it; while Brandt (Med. 
Zool. II. p. 87) had taken it for an os hyotdes, 
16 Doyere, loc. cit. p. 322, Pl. XIIL.-XV. 
